5,940 research outputs found
Local search for stable marriage problems with ties and incomplete lists
The stable marriage problem has a wide variety of practical applications,
ranging from matching resident doctors to hospitals, to matching students to
schools, or more generally to any two-sided market. We consider a useful
variation of the stable marriage problem, where the men and women express their
preferences using a preference list with ties over a subset of the members of
the other sex. Matchings are permitted only with people who appear in these
preference lists. In this setting, we study the problem of finding a stable
matching that marries as many people as possible. Stability is an envy-free
notion: no man and woman who are not married to each other would both prefer
each other to their partners or to being single. This problem is NP-hard. We
tackle this problem using local search, exploiting properties of the problem to
reduce the size of the neighborhood and to make local moves efficiently.
Experimental results show that this approach is able to solve large problems,
quickly returning stable matchings of large and often optimal size.Comment: 12 pages, Proc. PRICAI 2010 (11th Pacific Rim International
Conference on Artificial Intelligence), Byoung-Tak Zhang and Mehmet A. Orgun
eds., Springer LNA
Local search for stable marriage problems
The stable marriage (SM) problem has a wide variety of practical
applications, ranging from matching resident doctors to hospitals, to matching
students to schools, or more generally to any two-sided market. In the
classical formulation, n men and n women express their preferences (via a
strict total order) over the members of the other sex. Solving a SM problem
means finding a stable marriage where stability is an envy-free notion: no man
and woman who are not married to each other would both prefer each other to
their partners or to being single. We consider both the classical stable
marriage problem and one of its useful variations (denoted SMTI) where the men
and women express their preferences in the form of an incomplete preference
list with ties over a subset of the members of the other sex. Matchings are
permitted only with people who appear in these lists, an we try to find a
stable matching that marries as many people as possible. Whilst the SM problem
is polynomial to solve, the SMTI problem is NP-hard. We propose to tackle both
problems via a local search approach, which exploits properties of the problems
to reduce the size of the neighborhood and to make local moves efficiently. We
evaluate empirically our algorithm for SM problems by measuring its runtime
behaviour and its ability to sample the lattice of all possible stable
marriages. We evaluate our algorithm for SMTI problems in terms of both its
runtime behaviour and its ability to find a maximum cardinality stable
marriage.For SM problems, the number of steps of our algorithm grows only as
O(nlog(n)), and that it samples very well the set of all stable marriages. It
is thus a fair and efficient approach to generate stable marriages.Furthermore,
our approach for SMTI problems is able to solve large problems, quickly
returning stable matchings of large and often optimal size despite the
NP-hardness of this problem.Comment: 12 pages, Proc. COMSOC 2010 (Third International Workshop on
Computational Social Choice
PrivacyScore: Improving Privacy and Security via Crowd-Sourced Benchmarks of Websites
Website owners make conscious and unconscious decisions that affect their
users, potentially exposing them to privacy and security risks in the process.
In this paper we introduce PrivacyScore, an automated website scanning portal
that allows anyone to benchmark security and privacy features of multiple
websites. In contrast to existing projects, the checks implemented in
PrivacyScore cover a wider range of potential privacy and security issues.
Furthermore, users can control the ranking and analysis methodology. Therefore,
PrivacyScore can also be used by data protection authorities to perform
regularly scheduled compliance checks. In the long term we hope that the
transparency resulting from the published benchmarks creates an incentive for
website owners to improve their sites. The public availability of a first
version of PrivacyScore was announced at the ENISA Annual Privacy Forum in June
2017.Comment: 14 pages, 4 figures. A german version of this paper discussing the
legal aspects of this system is available at arXiv:1705.0888
Approximation algorithms for hard variants of the stable marriage and hospitals/residents problems
When ties and incomplete preference lists are permitted in the Stable Marriage and Hospitals/Residents problems, stable matchings can have different sizes. The problem of finding a maximum cardinality stable matching in this context is known to be NP-hard, even under very severe restrictions on the number, size and position of ties. In this paper, we describe polynomial-time 5/3-approximation algorithms for variants of these problems in which ties are on one side only and at the end of the preference lists. The particular variant is motivated by important applications in large scale centralised matching schemes
An 8/5 approximation algorithm for a hard variant of stable marriage
When ties and incomplete preference lists are permitted in the Stable Marriage problem, stable matchings can have different sizes. The problem of finding a maximum cardinality stable matching in this context is NP-hard, even under very severe restrictions on the number, size and position of ties. In this paper, we describe a polynomial-time 8/5-approximation algorithm for a variant in which ties are on one side only and at the end of the preference lists. This variant is motivated by important applications in large scale centralized matching schemes
The Rise of Certificate Transparency and Its Implications on the Internet Ecosystem
In this paper, we analyze the evolution of Certificate Transparency (CT) over
time and explore the implications of exposing certificate DNS names from the
perspective of security and privacy. We find that certificates in CT logs have
seen exponential growth. Website support for CT has also constantly increased,
with now 33% of established connections supporting CT. With the increasing
deployment of CT, there are also concerns of information leakage due to all
certificates being visible in CT logs. To understand this threat, we introduce
a CT honeypot and show that data from CT logs is being used to identify targets
for scanning campaigns only minutes after certificate issuance. We present and
evaluate a methodology to learn and validate new subdomains from the vast
number of domains extracted from CT logged certificates.Comment: To be published at ACM IMC 201
New Kids on the Net. Deutschsprachige Philosophie elektronisch\ud
Mailing lists tend to be shaped by core groups of dedicated participants, developing their interests and opinions in front of a predominantly receptive audience of subscribers. A new kind of communicative praxis is established on top of some guidelines on how computers should exchange data: participation in quasi-instantaneous, globally distributed, non-hierarchical discursive interchange. Computer networks, as is well known, are not confined by any historical or geographical borders. As a consequence, the cultural impact of the technical devices seems to affect arbitrary collections of users availing themselves of the necessary equipment and know-how. One of the most dazzling experiences of communication on the net, it has correctly been pointed\ud
out, is its global egalitarianism. While it is true that large parts of the planet are still excluded and the predominance of the English language imposes important\ud
constraints on the participants, it is difficult to avoid an initial euphoria, a cosmopolitan state of mind, as one becomes familiar with a machinery that can support spatially unlimited cooperation between equals with a minimum of\ud
administrative overhead
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